Support is requested for participation in all clinical and laboratory investigative activities of the Pediatric Oncology Group (POG). The POG is a new pediatric cooperative group comprising the pediatric components of the SWOG and the CALGB, with the addition of several new institutions. Specifically, these funds will assist our efforts in cooperative cancer therapy trials which utilize a combination of surgery and/or radiation therapy and/or chemotherapy for the treatment of leukemias, lymphomas, solid tumors and brain tumors. Emphasis will be placed on integrated multimodality treatment programs in phase III randomized prospective studies. We shall also participate in pilot and group wide phase II studies of new chemotherapeutic agents. Support will permit us to enter the maximum number of patients on study and ensure complete documentation of patient data: will permit members to attend Pediatric Oncology Group meetings and to participate in working sub-committees, protocol planning committees and study writing committees; and will permit group wide studies of methotrexate pharmcology to be carried out.